Water-enhancing, fire-suppressing hydrogels

ABSTRACT

The present application provides water-enhancing, fire-suppressing hydrogels that are formulated to minimize toxicity and negative environmental impact. The present application provides a composition comprising: (i) at least one thickening agent; (ii) at least one liquid medium; and, optionally, (iii) one or more suspending agents, wherein the composition consists of &gt;75%, by weight, consumer-grade components and wherein the composition is a concentrate that can be mixed with water or an aqueous solution to form a fire-suppressing, water-enhancing hydrogel. Each of the at least one thickening agent, suspending agent and liquid medium can be non-toxic and biodegradable. Also provided are the fire-suppressing, water-enhancing hydrogel and methods of production and use thereof during fire fighting or fire prevention.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is Continuation Application of U.S. patentapplication Ser. No. 16/811,198 filed Mar. 6, 2020, which is aDivisional Application of U.S. patent application Ser. No. 16/192,383filed Nov. 15, 2018, which is a Continuation Application of U.S. patentapplication Ser. No. 15/529,863 filed May 25, 2017, which is a NationalPhase application filed under 35 U.S.C. § 371 of PCT InternationalApplication No. PCT/CA2015/051235 with an International Filing Date ofNov. 26, 2015, which claims the benefit of priority of U.S. ProvisionalApplication No. 62/084,965, filed Nov. 26, 2014, the entire contents ofwhich are hereby incorporated by reference as though fully set forthherein in their entirety.

FIELD OF THE INVENTION

The present application pertains to the field of firefighting agents.More particularly, the present application relates to water-enhancing,fire-suppressing hydrogels.

INTRODUCTION

Fire is a threat to life, property, and natural, suburban, and urbanlandscapes worldwide. Forest, brush, and grassland fires destroy acresof natural and suburban landscapes each year; with the total average ofacres lost to wildfire increasing since about 1984[http://climatedesk.org/2014/06/this-is-how-much-america-spends-putting-out-wildfires].This destruction is not only in terms of a loss of timber, wildlife andlivestock, but also in erosion, disruption to watershed equilibria, andrelated problems in natural environments. In suburban, urban, andindustrial areas, fire can result in billions of dollars in damage fromloss of lives, property, equipment, and infrastructure; not only fromthe fire itself, but also from water used to extinguish it.

Fire and its constructs are often described by the ‘Fire Tetrahedron’,which defines heat, oxygen, fuel, and a resultant chain reaction as thefour constructs required to produce fire; removing any one will preventfire from occurring. There are five classes of fire: Class A, whichcomprises common combustibles, such as wood, cloth, etc.; Class B, whichcomprises flammable liquids and gases, such as gasoline, solvents, etc.;Class C, which comprises live electrical equipment, such as computers,etc.; Class D, which comprises combustible metals, such as magnesium,lithium, etc.; and, Class K, which comprises cooking media, such ascooking oils and fats. Water is usually a first line of defence againstcertain classes of fires (e.g. class A), and is used not only toextinguish said fires, but also prevent them from spreading; due, atleast in part, to water's ability to absorb heat via its high heatcapacity (4.186 J/g° C.) and heat of vaporization (40.68 kJ/mol), thuscooling surfaces, as well as its ability to physically displace airsurrounding a fire, and deprive it of oxygen.

There are, however, disadvantages to using water to fight fire and/orprevent it from spreading to nearby structures. Often, most of the waterdirected at a structure does not coat and/or soak into the structureitself to provide further fire protection, but rather is lost to run offand wasted; what water does soak into a structure is usually minimal,providing limited protection as the absorbed water quickly evaporates.Further, water sprayed directly on a fire tends to evaporate at thefire's upper levels, resulting in significantly less water penetratingto the fire's base to extinguish it.

Consequently, significant manpower and local water resources can beexpended to continuously reapply water on burning structures toextinguish flames, or on nearby structures to provide fire protection.

To overcome water's limitations as a fire-fighting resource, additiveshave been developed to enhance water's capacity to extinguish fires.Some of these additives include water-swellable polymers, such ascross-linked acrylic or acrylamide polymers, that can absorb many timestheir weight in water, forming gel-like particles; once dispersed inwater, these water-logged particles can be sprayed directly onto a fire,reducing the amount of time and water necessary for fighting fires, aswell as the amount of water run off (for example, see U.S. Pat. Nos.7,189,337 and 4,978,460).

Other additives include acrylic acid copolymers cross-linked withpolyether derivatives, which are used to impart thixotropic propertieson water (for examples, see U.S. Pat. Nos. 7,163,642 and 7,476,346).Such thixotropic mixtures thin under shear forces, allowing them to besprayed from hoses onto burning structures or land; once those shearforces are removed, the mixture thickens, allowing it to cling to, andcoat, surfaces, extinguish flames, and prevent fire from spreading, orthe structure from re-igniting.

Additives employed in current commercial products are not naturallysourced and are not readily biodegradable. A drawback associated withthese polymeric additives is that they can persist in the environmentfollowing their use during firefights, and/or can bio-accumulate orcause ill effects on surrounding environment.

Research into non-toxic, biodegradable, renewable, and/ornaturally-sourced materials has increased in an effort to replacehalogen-based/synthetic firefighting materials, and reduce theirenvironmental impact. Thermoplastic starches (TPS), such as modifiedstarches or starch-copolymers, have been proposed by those skilled inthe art as one such non-toxic, biodegradable, renewable, and/ornaturally-sourced material. Starch is not a natural thermoplastic atroom temperature, however, at elevated temperatures it can form ahydrogel when mixed with water; alternatively, it can be further blendedwith plasticizers, such as glycerol, to also form hydrogels [Wu, K.; elal. Ind. Eng. Chem. Res. 2009, 48, 3150-3157]. Blending TPS withpolymers such as polyvinylalcohol (PVA) [Bao, Z.; el al. Adv. Mater.Res. 2012, 518-523, 817-820] or polylactide (PLA) [Wu, K.; el al. Ind.Eng. Chem. Res. 2011, 50, 713-720] can reportedly increase TPS'hydrophilic properties, and turns TPS into intumescent (swells upon heatexposure) flame retardant materials. It has also been reported that, ifTPS are reinforced with biodegradable natural fibers [Katalin, B.; elal, Polimery, 2013, 58, 385-394], its flammability can be reduced.Alternatively, TPS can be blended with clay to reduce its flammability;a nano-size clay (Cloisite 30B) can be solvent-blended with starch toimprove its thermal stability [Swain, S. k.; el al. Polym. Comp. 2013,Ahead of print]. Preparation of such modified starches, however, oftenrequires chemical reagents and advanced syntheses.

In turn, superabsorbent polymers have garnered much attention due totheir broad applications in hygienic products, agricultural adjuvant,and pharmaceuticals, etc [Liu, L. S.; el al. Polym. 2012, 4, 997-1011].They are also hydrogel materials: polymeric materials with the abilityto swell and retain a significant amount of water (up to 99.9% byweight) without dissolving in said water. As synthetic hydrogels are notgenerally biodegradable, there are a number of natural starch resourcesbeing investigated as potential hydrogels, such as: cornstarch [Kuang,J.; el al. Carbohydrate Polym. 2011, 83, 284-290], chitosan [Nanaki, S.G.; el al. Carbohydrate Polym. 2012, 1286-1294], guar gum [Bocchinfuso,G.; el al. J. Phy. Chem. B2010, 114, 13059-13068], cellulose and itsderivatives [Sadeghi, M. el al. J. Appl. Polym. Sci. 2008, 108,1142-1151], alginate and its derivatives, etc. Only a few of thesestarches are commercially available (e.g. cellulose derivatives,hydroxyethyl-starch)

There remains a need for fire fighting or fire retardant compositionsmade from water-enhancing additives that are naturally sourced and/orconsumer grade, which are non-toxic and/or readily biodegradable.

The above information is provided for the purpose of making knowninformation believed by the applicant to be of possible relevance to thepresent invention. No admission is necessarily intended, nor should beconstrued, that any of the preceding information constitutes prior artagainst the present invention.

SUMMARY OF THE INVENTION

An object of the present invention is to provide water-enhancing,fire-suppressing hydrogels. In accordance with an aspect of the presentapplication, there is provided a composition comprising: (i) at leastone thickening agent; (ii) at least one liquid medium; and, optionally,(iii) one or more suspending agents, wherein the composition consistsof >75%, by weight, consumer-grade components and wherein thecomposition is a concentrate that can be mixed with water or an aqueoussolution to form a fire-suppressing, water-enhancing hydrogel. Each ofthe at least one thickening agent, suspending agent and liquid mediumcan be non-toxic and biodegradable.

In one embodiment, the concentrated composition of claim 1, wherein thecomposition comprises: (i) 10-75 wt % of at least one thickening agent;(ii) 0-10 wt % of at least one suspending agent; and (iii) 15-90 wt % ofat least one liquid medium. The concentrate can further comprise one ormore additives, each of which is optionally non-toxic and biodegradable.Examples of additives that can be incorporated in the concentrate are:salts an anti-microbial agents, an anti-fungal agents, antioxidants,colorants, clays, dispersing agents. These additives can be incorporatedalone or in any combination of any two or more additives.

In certain embodiments the concentrate composition has a viscosity of≥1000 cP, ≥2500 cP, ≥5000 cP, or ≥10 000 cP, when measured using aBrookfield LVDVE viscometer with a CS-34 spindle at 6.0 rpm.

The thickening agent can be a solid or a liquid under ambientconditions. Suitable thickening agents include, for example, gums,starches or combinations one or more gums and one or more starches.Suitable gums include, but are not limited to guar gums, xanthan gums,sodium alginate, agar, or locust bean gums, or combinations thereof. Inspecific examples of the present concentrate, the thickening agentcomprises xanthan gum, gaur gum, or a combination thereof.

Suitable starches that can be used as thickening agents in the presentconcentrate include, but are not limited to cornstarch, potato starch,tapioca, rice starch, carboxymethylcellulose sodium salt, or anycombination thereof. In specific examples of the present concentrate,the thickening agent comprises cornstarch.

In certain embodiments, the concentrate composition comprises asuspending agent, which can be a surfactant, emulsifier or both. Forexample, the concentrate can comprises a suspending agent, whichcomprise lecithin, lysolecithin, polysorbate, sodium caseinate,monoglyceride, fatty acid, fatty alcohol, glycolipid, or protein, or anycombination thereof. In a particular example, the suspending agent islecithin.

In accordance with another embodiment, the liquid medium in theconcentrate is an edible oil, glycerol, or low molecular weightpolyethylene glycol (PEG), or any combination thereof. In a particularembodiment, the PEG is PEG200-PEG400. In another embodiment, the edibleoil is a nut oil, seed oil, plant oil, vegetable oil, or canola oil, orcombination thereof. In a specific example the concentrate comprises anedible oil, which is canola oil.

In a particular embodiment, the concentrate comprises: (i) 15-25 wt %xanthan gum; (ii) 10-20 wt % guar gum; (iii) 10-20 wt % cornstarch; (iv)1-5 wt % lecithin; and (v) 30-64 wt % canola oil. Optionally, theconcentrate additionally comprises 0.1-2.5% of a fatty alcohol, such asoleyl alcohol.

The present concentrate composition is formulated to minimize toxicityand negative environmental impact. Accordingly, in certain embodiments,the composition consists of >80%, >85%, >90%, >95%, >98% orapproximately 100%, by weight, consumer-grade components.

In accordance with another aspect, there is provided a hydrogel,comprising: about 0.1-30 wt % of the concentrate composition describedabove; and 70-99.9 wt % of water or an aqueous solution, wherein thehydrogel is a water-enhancing, fire-suppressant, useful forfire-fighting, fire-suppression, and/or fire-prevention. In certainembodiments, the hydrogel comprises the concentrate composition at aweight percentage of from about 0.1 to about 1 wt %, from about 1 toabout 5 wt %, from about 5 to about 10 wt % or from about 15 to about 30wt %. In a particular embodiment, the concentrate's weight percentage inthe hydrogel is 1-5 wt %.

In certain embodiments, the hydrogel's viscosity is 0.1-1 cP, 1-5 cP,5-10 cP, 10-15 cP, 15-30 cP, 30-60 cP, 60-90 cP, 90-120 cP, 120-150 cP,or >150 cP when measured with a Viscolite 700 viscometer. The hydrogelcan exhibit non-Newtonian fluidic, pseudoplastic and/or thixotropicbehaviour.

In one embodiment, the viscosity of the decreases with application ofstress and, optionally, increases after the stress ceases or has beenremoved. The viscosity increase can occur over a short time period, suchas ≤60 s, ≤40 s, ≤20 s, ≤10 s, or ≤5 s.

In one embodiment, the hydrogel adheres to surfaces to which it isapplied. In one example, the hydrogel having decreased viscosity isapplied (e.g., by spraying) to flow into, coat, and/or adhere to surfaceabrasions and/or gaps. As a result of the application process finishing,the stress on the hydrogel ceases and the viscosity of the hydrogel canincrease such that the hydrogel remains on the surfaces to which it wasapplied without running off, or with minimal runoff in comparison tocurrently used fire-suppressing formulations.

The hydrogel described herein functions to suppress and/or extinguishfire, when applied to a burning surface, or functions to prevent fireignition when applied to a non-burning surface.

In accordance with another aspect, there is provided method of making awater-enhancing, fire-suppressing hydrogel comprising: (i) combining theconcentrate composition described herein with water or an aqueoussolution; and (ii) mixing the concentrate and aqueous solution to obtainan essentially homogenous hydrogel. In one embodiment, the weightpercent of the concentrate is selected to achieve a particular viscosityand/or surface adhesion in the hydrogel. In a particular example, theconcentrate is introduced such that its weight percent in the finalhydrogel is from about 1 to about 5 wt %.

In one embodiment, the step of combining comprises manual addition ordirect, mechanical injection of the concentrate. Depending on theequipment used, the water or aqueous solution is held in a tank externalto, or on-board, a vehicle or portable device used in fire-fighting.

In one embodiment, the mixing step comprises manual agitation;mechanical agitation, circulation or stirring, or application of shearforces (for example, from pressurized flow through a fire hose).

In accordance with another aspect, there is provided a kit, comprising:(i) the concentrate composition as described herein in a containersuitable to permit or facilitate mixing of the concentrate compositionwith water or an aqueous solution; and (ii) directions for producing ahydrogel from the concentrate composition.

BRIEF DESCRIPTION OF THE FIGURES

For a better understanding of the present invention, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 depicts graphical results of canola-based hydrogels' viscositychanging with time as the hydrogel is being discharged from a 100 ftfire hose;

FIG. 2 depicts a glass adhesion test result for a hydrogel formed from a3 wt % canola-based liquid concentrate;

FIG. 3 depicts graphical results of canola-based hydrogels' viscositychanging with time as the hydrogel is being discharged from a 200 ftfire hose;

FIG. 4 depicts graphical results of PEG300-based hydrogels' viscositychanging with time as the hydrogel is being discharged from a 200 ftfire hose;

Table 1 outlines general formulations of select liquid concentratesidentified for further development;

Table 2 outlines screening results for various concentrate thickeningagents;

Table 3 outlines initial liquid concentrate formulations and adhesiontest results;

Table 4 outlines PEG/glycerol-based hydrogels with salt additivesadhesion test results;

Table 5 outlines canola-based hydrogels with salt additives adhesiontest results;

Table 6 outlines settlement and front-flow test results of liquidconcentrates after lecithin addition;

Table 7 outlines viscosity and adhesion test results for select liquidconcentrates;

Table 8 outlines effects of starch on liquid concentrate viscosity andadhesion;

Table 9 outlines effect of xanthan gum particle size on viscosity;

Table 10 outlines effect of increasing solids content in liquidconcentrates on viscosity;

Table 11 outlines viscosities of 20 L batches of a canola-based liquidconcentrate;

Table 12 outlines a PEG300-based liquid concentrate formulation and itsviscosity; and

Table 13 outlines initial flame tests carried out using initial hydrogelformulations.

DETAILED DESCRIPTION

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs.

As used in the specification and claims, the singular forms “a”, “an”and “the” include plural references unless the context clearly dictatesotherwise.

The term “comprising” as used herein will be understood to mean that thelist following is non-exhaustive and may or may not include any otheradditional suitable items, for example one or more further feature(s),component(s) and/or ingredient(s) as appropriate.

As used herein, the term “consumer-grade components” refers tofood-grade, personal care-grade, and/or pharmaceutical-grade components.The term “food-grade” is meant to mean safe for use in food, such thatingestion does not, on the basis of the scientific evidence available,pose a safety risk to the health of the consumer. The term “personalcare-grade” is meant to mean safe for use in topical application suchthat, topical application does not, on the basis of the scientificevidence available, pose a safety risk to the health of the consumer.The term “pharmaceutical-grade” is meant to mean safe for use in apharmaceutical product administered by the appropriate route ofadministration, such that administration does not, on the basis of thescientific evidence available, pose a safety risk to the health of theconsumer.

As used herein, the term “non-toxic” is meant to mean non-poisonous,non-hazardous, not composed of poisonous materials that could harm humanhealth if exposure is limited to moderate quantities and not ingested.Non-toxic is meant to connote harmlessness to humans and animals inacceptable quantities if not ingested and even upon ingestion, does notcause immediate serious harmful effects to the person or animalingesting the substance. The term non-toxic is not meant to mean able tobe swallowed or injected or otherwise taken in by animals, plants, orother living organisms. The term non-toxic may mean the substance isclassified as non-toxic by the Environmental Protection Agency (EPA),the World Health Organization (WHO), the Food and Drug Administration(FDA), Health Canada, or the like. The term non-toxic is therefore notmeant to mean non-irritant or not causing irritation when exposed toskin over prolonged periods of time or otherwise ingested.

When used to describe the concentrate or the resultant fire-suppressinghydrogel of the present application, the term non-toxic indicates thatthe composition is non-toxic to humans at concentrations and exposurelevels required for effective use as fire-fighting, suppressing, and/orpreventing agents, without the need for protective gear.

The term “surface abrasion(s)” as used herein refers to any deviationfrom a surface's structural norm, such as, but not limited to, holes,fissures, gaps, gouges, cuts, scrapes, cracks, etc.

As used herein, the term “surface adhesion” refers to the ability of acomposition to coat and/or adhere to a surface at any orientation (e.g.,vertical cling). In referring to the hydrogel compositions of thepresent application, the term “surface adhesion” further refers to theability of the hydrogel to adhere to a surface such that adequate firefighting, suppression, and/or protection is afforded as a result of thesurface being coated by the hydrogel.

As detailed below, the presently disclosed hydrogel, and concentrateused to prepare the hydrogel, have been formulated to be non-toxic andenvironmentally benign. This has been achieved through the presentfinding that consumer-grade materials can be used successfully toprepare a water-enhancing fire-suppressant. Accordingly, the presentcompositions overcome many of the drawbacks associated with previousattempts at non-toxic, biodegradable, renewable, and/ornaturally-sourced fire-suppressing agents.

Hydrogel-Forming Concentrates and their Components

The present application provides a concentrate composition, for use inproducing hydrogels in situ, which comprises >75% non-toxic,consumer-grade components. In certain embodiments, the components of theconcentrate composition can also be biodegradable, renewable and/ornaturally-sourced. Optionally, the concentrate compositioncomprises >80%, >85%, >90%, >95% or >98% non-toxic, consumer-gradecomponents.

In one aspect, the concentrate is a liquid concentrate that comprises atleast one thickening agent, a liquid medium, and at least one suspendingagent. Such a liquid concentrate can be, for example, a solution, asuspension or a slurry. Alternatively, the concentrate is a powder orother solid mixture, which comprises at least one thickening agent andat least one suspending agent. In either alternative, the concentrate isformulated to be mixed with water, or an aqueous solution, to form ahydrogel having fire suppressant or retardant properties.

Thickening Agents

Hydrogel-forming concentrates, as herein described, require at least onespecies to act as a thickening agent to aid ingenerating a hydrogel. Athickening agent can be, for example, a polymer. Starch, which is abiodegradable, naturally-sourced polymer, can form gels in the presenceof water and heat. Starch-based hydrogels can act as fire retardants dueto their high water retaining and surface-adhesion capabilities [IoannaG. Mandala (2012). Viscoelastic Properties of Starch and Non-StarchThickeners in Simple Mixtures or Model Food, Viscoelasticity—From Theoryto Biological Applications, Dr. Juan De Vicente (Ed.), ISBN:978-953-51-0841-2, InTech, DOI: 10.5772/50221. Available from:http://www.intechopen.com/books/iviscoelasticity-from-theory-to-biological-applications/iviscoelastic-properties-of-starch-and-non-starch-thickeners-in-simple-mixtures-or-model-food].One example of a natural starch-based, hydrogel-forming thickening agentis carboxymethylcellulose sodium salt, which has found use in personallubricants, toothpastes, and ice creams as a thickener; it is food-gradeand biodegradable, and can absorb water at concentrations as low as 1%in water. Other types of starch that are viable for use in the presentconcentrate include, but are not limited to, corn starch, potato starch,tapioca, and/or rice starch.

Other viable naturally sourced, biodegradable thickening agents includenatural gums, such as, but not limited to, guar gum, xanthan gum, sodiumalginate, agar, and/or locust bean gum, some of which are used asthickeners in food, pharmaceutical and/or cosmetic industries. Forexample, guar gum is sourced primarily from ground endosperms of guarbeans, and reportedly has a greater water-thickening potency thancornstarch; xanthan gum is produced by Xanthomonas camperstris [Tako, M.et al. Carbohydrate Research, 138 (1985) 207-213]. At lowconcentrations, xanthan gum or guar gum can confer an increase inviscosity to aqueous solutions; and, that imparted viscosity can changedepending on what shear rates the solutions are exposed to, due to thegums' shear-thinning or pseudoplastic behaviour. Further, it has beenobserved that mixtures of xanthan and guar gum exhibit a synergisticeffect: in addition to their shear-thinning properties, mixtures ofxanthan and guar gum impart higher viscosities to aqueous solutions thaneach gum individually [Casas, J. A., et al. J Sci Food Agric80:1722-1727, 2000].

Liquid Medium

As noted above, the hydrogel-forming concentrate can be a mixture ofsolid components (such as a powder), or a liquid suspension/solution.Either a solid or liquid concentrate could be mixed with water to form awater-enhancing, fire-suppressing hydrogel; however, it would beunderstood by one skilled in the art that pre-dissolving orpre-suspending a concentrate's components in a liquid medium canfacilitate its mixing with water, and potentially increase the rateand/or ease at which a hydrogel forms. Examples of non-toxic,consumer-grade liquid mediums include, but are not limited to, edibleoils, such as nut/seed oils, or vegetable/plant oils, glycerol, and lowmolecular weight polyethylene glycol (PEG).

In addition to being naturally-sourced and/or food-grade, liquid mediumssuch as vegetable oil, glycerol, and PEG resist freezing at sub-zerotemperatures; thus, concentrates formed with such liquid mediums canmaintain their utility for forming hydrogels under winter and/or arcticconditions. Further, some liquid mediums, such as glycerol and PEG, arewater-miscible, which can also enhance the ability of the concentrate toeffectively mix with water and form a hydrogel.

In certain embodiments, the concentrate comprises a mixture of more thanone liquid media.

Suspending Agents

Hydrogel-forming liquid concentrates, formed from solid components(e.g., thickening agents) suspended or dissolved in a liquid medium(e.g., vegetable oil), may exhibit settling of solid components overtime. If such settling were to occur, the liquid concentrate can bephysically agitated in order to re-suspend or re-dissolve itscomponents. Alternatively, a suspending agent (e.g., surfactant oremulsifier), or a combination of suspending agents, can be added to theliquid concentrate to stabilize the composition, or to facilitatekeeping solid components suspended or dissolved in the liquid medium,either indefinitely, or for a length of time sufficient to maintain aconcentrate's utility for hydrogel formation.

Examples of non-toxic, consumer-grade surfactants and/or emulsifiersinclude, but are not limited to, lecithins, lysolecithins, polysorbates,sodium caseinates, monoglycerides, fatty acids, fatty alcohols,glycolipids, and/or proteins [Kralova, I., et al. Journal of DispersionScience and Technology, 30:1363-1383, 2009]. Such surfactants can beprovided as solids or liquids. The addition of a surfactant, orcombination of surfactants, to the concentrate, can increase theviscosity of the concentrate and/or increase the viscosity of thehydrogel formed following dilution of the concentrate with water. Thiseffect of the surfactant, or combination of surfactants, occurs as aresult of their suspension action, and/or by increasing the amount ofmaterial that can be included in the concentrate or the resultanthydrogel.

In certain embodiments, the surfactant(s) used in the concentrate is aliquid. As would be readily appreciated by one skilled in the art, suchliquid surfactants can be more easily mixed with the liquid medium of aliquid concentrate than can a solid surfactant. Accordingly, the liquidsurfactant(s) may, in some examples, be more effective at maintainingthe solid components in suspension and/or solution.

In certain embodiments, the concentrate contains more than onesurfactant. The surfactants can be all solid surfactants, all liquidsurfactants or a combination of liquid and solid surfactants.

Additives

Other components, or additives, can be added to the concentrate in orderto affect or alter one or more properties of the concentrate or thehydrogel formed from the concentrate. The appropriate additive(s) can beincorporated as required for a particular use. For example, additivescan be added to affect the viscosity and/or stability of theconcentrate, and/or the resultant hydrogel. Additional additives thatcan be incorporated in the present concentrate and hydrogel compositionsinclude, but are not limited to, pH modifiers, dispersing agents (e.g.,surfactants, emulsifiers, clays), salts, anti-microbial agents,anti-fungal agents and dyes/coloring agents. Specific, non-limitingexamples of non-toxic, consumer-grade additives include: sodium andmagnesium salts (e.g., borax, sodium bicarbonate, sodium sulphate,magnesium sulphate), which can affect hydrogel viscosity and/orstability [Kesavan, S. et al., Macromolecules, 1992, 25, 2026-2032;Rochefort, W. E., J. Rheol. 31, 337 (1987)]; chitosan or epsilonpolylysine, which can act as anti-microbials [Polímeros: Ciência eTecnologia, vol. 19, no 3, p. 241-247, 2009;http://www.fda.gov/ucm/groups/ifdagov-public/gfdagov-foods-gen/documents/document/ucm267372.pdf (accessed Sep. 26, 2014)], and pectin, which can aid in theformation of hydrogels.

As would be readily appreciated by a worker skilled in the art, theadditive(s) can be added to the concentrate, or the additive(s) can beadded during formation of the hydrogel, or to the additive(s) can beadded to the hydrogel.

The concentrate is prepared by mixing the components in any order,typically under ambient conditions. The relative amounts of eachcomponent, in particular the thickening agent, liquid agent, and, whenpresent, the suspending agent, are selected based, at least in part, onthe desired viscosity of the concentrate. Once formed, the concentratehas a shelf life of about 30 days, 1-3 months, 3-6 months, 6-9 months,9-12 months, 12-15 months, 15-18 months, 18-21 months, 21-24 months, or≥24 months.

Water-Enhancing, Fire-Suppressing Hydrogels

The present application further provides water-enhancing,fire-suppressing hydrogels formed from the concentrate described above,which comprise non-toxic, consumer-grade components. In one embodiment,the hydrogel is used to fight domestic, industrial, and/or wild fires byeliminating at least one construct of the “fire tetrahedron”; whichconsists of heat, fuel, oxygen, and chain reaction. In anotherembodiment, the hydrogel is applied to burning or fire-threatenedstructures, such as edifices and/or landscape components (e.g., trees,bushes, fences) via firefighting equipment. In one embodiment, thehydrogels described herein can be used to fight Class A fires (i.e.,wood and paper fires); in another embodiment, said hydrogels aresuitable for fighting Class B fires (i.e., oil and gas fires).

Hydrogel Formation and Application

A water-enhancing, fire-suppressing hydrogel as herein described can beformed by mixing a concentrate, as described above, with water or anaqueous solution. When applied using firefighting equipment, theconcentrate is mixed with the equipment's water supply, and then appliedto target objects (such as, structures, edifices and/or landscapeelements) to extinguish, suppress or prevent fire or to protect fromfire. Firefighting equipment useful in applying the hydrogels of thepresent application, comprises a means for mixing the concentrate withwater or an aqueous solution and means for spraying the resultanthydrogel onto the target objects. In one embodiment, the firefightingequipment additionally comprises a reservoir for holding the concentrateuntil required; the reservoir is in fluid communication with the mixingmeans such that the concentrate can be moved from the reservoir to themixing means for mixing with the water or aqueous solution. In anotherembodiment, the firefighting equipment additionally comprises means forintroducing water or an aqueous solution to the means for mixing, or areservoir fluidly connected to the means for mixing, such that the wateror aqueous solution can be moved from the reservoir to the mixing meansfor mixing with the concentrate. Non-limiting examples of firefightingequipment include spray nozzle-equipped backpacks, or sprinkler systems.The firefighting equipment can be mounted on or in a vehicle, such as, atruck, airplane or helicopter.

In accordance with one embodiment, in which the hydrogel is used forfirefighting using fire trucks, or other firefighting vehicles,including aircrafts, the herein described hydrogels are formed and usedvia the following, non-limiting process: the hydro-gel formingconcentrate is added to a truck's water-filled dump tank and/or otherportable tank, and mixed with the water via a circulating hose, orequivalent thereof; pumping the hydrogel, once formed, out of thetank(s), and applying the hydrogel to the target objects (e.g., edificesor landscape elements), via a hard suction hose, or equipment equivalentthereof.

In an alternative embodiment, the concentrate is added directly to avehicle's onboard water tank, either manually or via an injectionsystem, and mixed via circulation in the tank. In one example of thisembodiment, the injection system comprises an ‘after the pump’ system,which injects specified amounts of concentrate into water that haspassed through the vehicle's pump, and is about to enter the fire hose;friction of the water moving through the hose assists in mixing theconcentrate with the water to produce the hydrogel in the hose. Inanother specific example, the injection system pumps the concentratefrom a dedicated reservoir to an injection pipe that introducesconcentrate into the water just prior to the hose line; a computerizedsystem calculates water flow via a flow meter on said injection pipe toinject required amounts of concentrate into the pipe and hose stream viaa specially designed quill.

Further, fire-fighting vehicles suitably equipped with an in-lineinjection system, allow the concentrate to be added directly in-linewith the water, which can then be mixed via physical agitation and/orshear forces within the hose itself.

As would be readily appreciated by a worker skilled in the art, althoughthe methods for hydrogel formation described above may specificallyrefer to a fire fighting truck, such methods are equally applicable tofirefighting using aircraft, such as airplanes or helicopters, wherewater, or other aqueous solutions, is air dropped from a tank eithercontained within, or suspended by, the aircraft.

In another embodiment, the hydrogel formulation is made from theconcentrate at the time of firefighting using firefighting backpacks. Inthis embodiment the concentrate can be added to directly to thebackpack's water-filled reservoir, and manually or mechanically shakento form the hydrogel. Once formed, the hydrogel can be applied torequisite objects, or surfaces, via the backpacks' spray-nozzle.

In another embodiment, the concentrates as herein described can be addedto a sprinkler system's water supply, such that, upon activation as aresult heat, smoke, and/or fire detection, the system sprays thehydrogel, as described herein, rather than simply water (as in currentpractice). In one embodiment, once a sprinkler system is activated, adedicated pump system injects concentrate into the sprinkler's watersystem, producing a hydrogel with properties compatible with thesprinkler's flow requirements, prior to being applied to an object orarea (e.g., an edifice, room or landscape area). In another embodiment,the sprinkler system comprises sprinkler heads designed to provide anoptimized spray pattern for applying a hydrogel to an object or area(e.g., an edifice, room or landscape area).

In yet another embodiment, a sprinkler system for applying the hydrogelsas described here in comprises: a dedicated pump for injectingconcentrate, as described herein, into the sprinkler's water system; asprinkler head designed to provide an optimized spray pattern forhydrogel application; a computerized system to calculate water and/orhydrogel flow; a flow meter to detect water flow in dry pipes; and, apoint of injection designed to introduce the concentrate into the waterin such a way that is compatible with the sprinkler system and itsintended use.

Hydrogel Firefighting Properties

The herein provided hydrogels, as formed from the concentrates alsoprovided herein, are suitable for use as firefighting agents due totheir physical and/or chemical properties. The hydrogels are moreviscous than water, and generally resist evaporation, run-off, and/orburning when exposed to high temperature conditions (e.g., fire), due totheir water-absorbing, viscosity-increasing components. These hydrogelsalso exhibit shear-thinning, thixotropic, pseudoplastic, and/ornon-Newtonian fluidic behaviour, such that their viscosity decreaseswhen they are subjected to stresses, such as, but not limited to, shearstresses, wherein their viscosity increases again when those stressesare removed.

Consequently, once formed, the present hydrogels can be sprayed viahoses and/or spray-nozzles onto burning objects (e.g., edifices orlandscape elements) in a manner similar to water; and, once thehydrogels are no longer subjected to the stresses of being sprayed,their viscosity will increase to be greater than that of water. As aresult, the hydrogels can coat and cling, at virtually any angle, tosurfaces they are applied to, allowing them to extinguish fires bydisplacing oxygen and cooling surfaces, prevent fire flash-over, and/orfurther protect surfaces from re-ignition via the hydrogels' generalresistance to evaporation, run-off, and/or burning.

Further, as the viscosity increase would not be instantaneous, thehydrogels can ‘creep’ or ‘ooze’ into surface abrasions or structuralgaps, such as, but not limited to, cracks, holes, fissures, etc., in anedifice or landscape element, coating and protecting surfaces that wouldotherwise be difficult to protect with water, or other firefightingagents such as foams, due to evaporation or run-off. This willcontribute an element of penetrative firefighting to a firefighter'sarsenal: once the hydrogel's viscosity has increased, it will form aprotective layer in, on, under and/or around said cracks, surfaceabrasions, structural gaps or the like. Also, use of the hereindescribed hydrogels can minimize water damage to surfaces, since use ofthe hydrogels would replace the direct use of water in firefighting.

In one example, the hydrogel is applied at the head of an approachingfire, either as a fire break or to protect a property (e.g., cottage,house, or commercial or municipal building). Firefighters can proceedvia “coat and approach” to protect Firefighters inside a circumferenceset by a coating of the hydrogel, allowing the Firefighters to create aprotected route of egress.

To gain a better understanding of the invention described herein, thefollowing examples are set forth. It should be understood that theseexamples are for illustrative purposes only. Therefore, they should notlimit the scope of this invention in any way.

EXAMPLES

General Experimental

Materials

All materials used were naturally sourced, except polyethelene glycol(PEG200 or PEG300), and glycerol. PEG 200/300 and glycerol arenon-flammable liquids with low toxicity and are available infood/personal-care/pharmaceutical grades that are eitherfood/food-contact/personal-care/pharmaceutical additives. Experimentswere performed with chemical and/or analytical grade polyethylene glycoland glycerol; however, their chemical/physical properties wereconsidered to be equivalent to their food grade forms. Fresh tap waterwas used directly without any further purification. All chemicals wereused as received from commercial suppliers: xanthum gums (food grade, PO#DW-456270, Univar, 17425 NE Union Hill Road, Redmond, Wash.; Bulk BarnCanada); guar gum (P. L. Thomas&Co. Inc., 119 Head Quarters Plaza,Morristown, N.J.; Bulk Barn Canada); corn starch (Bulk Barn Canada);canola oil (FreshCo, Kingston, ON, Canada); PEG200 (Sigma-Aldrich,Oakville, ON, Canada); PEG300 (Sigma-Aldrich, Oakville, ON, Canada); andglycerol PEG200 (Sigma-Aldrich, Oakville, ON, Canada).

General Method for Producing Liquid Concentrates

Liquid concentrates were composed of at least four types of materials:thickening agents (e.g. gums), starches, liquid mediums, and optionally,other naturally-sourced and/or biodegradable additives (e.g.surfactants). All dry ingredients (e.g. gums, starch, etc.) weremeasured and combined in a beaker. Said ingredients were slowly mixedwith a spatula until a reasonably homogenous dry mixture was obtained. Arequired amount of a select liquid medium (e.g. canola oil, PEG, etc.)was measured using a graduate cylinder, then added to the beakercontaining said dry mixture, and stirred slowly with a spatula until nodry powder or separated liquid medium was observed. The liquidconcentrate was then considered ready for use. General formulations ofselect liquid concentrates are outlined in Table 1.

General Method for Producing Hydrogels

Generating a hydrogel from an aforementioned liquid concentrate involvedmixing the liquid concentrate (3 g) with fresh tap water (97 g) in a 150mL beaker. A IKA T25 homogenizer was then used to thoroughly mix thecomponents together (8600 rpm for 10 seconds), after which a hydrogelwas formed.

General Test Methods for Evaluating Liquid Concentrates and/or Hydrogels

Viscosity Tests

A liquid concentrate's viscosity was determined using a Brookfield LVDVEviscometer with a CS-34 spindle. Each sample was added to a small sampleadapter, and viscosity was tested at 6.0 rpm at room temperature.

Adhesion on Glass

To test a hydrogel's glass adhesion, a 3×1 inch (L×W) microscope glassslide was weighed before the slide was dipped into a hydrogel to a depthof 1.5 inches for 60 seconds. After the glass slide was removed from thehydrogel, it was suspended for 10 minutes before being weighed again.Mass of hydrogel remaining adhered to the slide was calculated fromdifference in weight, before and after.

Settlement Test

Each liquid concentrate is a suspension, from which solid ingredientscould settle out slowly over time, resulting in a bi-phasic mixture witha liquid layer on top. A settlement test was used to quantify separationin said liquid concentrates. Each tested liquid concentrate was added toa 100 mL graduate cylinder. As settling occurred in the cylinder, volumeof said liquid top layer could be continuously recorded until settlementwas complete. Test results are shown as top layer volume in total volumeof liquid concentrate.

Front Flow Test

Each sample from a Settlement Test was then used in a Front-Flow Test toestablish which samples offered minimal settlement while maintaininggood flow. Liquid concentrates that had been tested for settling werethen emptied, by inversion, over a pre-weighed beaker for one minute:after which, a total mass of liquid concentrate transferred to thebeaker was recorded. Any liquid concentrates having good flow andminimal settlement were considered viable formulations for furtherconsideration.

Example 1: Initial Screening of Liquid Concentrate Components

Thickening Agent Screening

Initial screening of thickening agents included xanthan gum, guar gum,carboxymethylcellulose sodium salt, or combinations thereof. A hydrogelwas prepared from a 1 wt % liquid concentrate comprising each thickeningagent independently, or a combination thereof (see Table 2), by blendingthe concentrate with water for 10 seconds (1 g of liquid concentrate in99 g of water).

Xanthan gum and guar gum produced hydrogels very quickly (within 10seconds using a homogenizer at 8600 rpm), though guar gum's hydrogel wasless viscous than that of xanthum gum (Table 2). Carboxymethylcellulosesodium salt did not form a hydrogel after 10 seconds, however a clearhydrogel was obtained after an hour. A combination of guar gum withxanthan gum displayed a synergistic effect with respect to hydrogelformation, an effect that has been previously observed and documented bythose skilled in the art [Tako, M. et al. Carbohydrate Research, 138(1985) 207-213].

In a qualitative test, it was observed that hydrogels formed from 1 wt %guar gum and xanthan gum respectively appeared to have a similarconsistency and/or viscosity as a hydrogel formed from 1 wt %polyacrylic acid.

Liquid Mediums Screening

For use in liquid concentrates, naturally-sourced and/or biodegradableoils such as, but not limited to, canola oils were considered as liquidmediums due to their expected low cost and relative abundance. Such oilstypically have limited solubility in water, however, and as such, watersoluble alternatives were also considered, such as, but not limited to,PEG200, PEG300 and glycerol.

Initial Liquid Concentrate Formulations

Using the aforementioned thickening agents and liquid mediums, fourformulations were created using a minimum amount of liquid medium, eachof which were evaluated by glass adhesion (see Table 3).

As outlined in Table 3, a high adhesion result was obtained fromFormulation 2, with canola oil as its liquid medium. Formulation 2 hadcomparable, if not greater, glass adhesion properties to that ofcommercial products TetraKO™ and Barricades™. It was observed thatFormulations 3 and 4 generated hydrogels more efficiently than otherformulations; without wishing to be bound by theory, it was postulatedthat this was due to PEG200 and glycerol's water miscibility. Further,it has been observed by those skilled in the art that xanthum gum'sviscosity and stability increases with addition of electrolytes (e.g.sodium or magnesium salts); as such, magnesium sulfate, sodium sulphate,and borax were used as additives, and the resultant hydrogels tested(see Tables 4 and 5) [Kesavan, S. et al., Macromolecules, 1992, 25,2026-2032; Rochefort, W. E., J. Rheol. 31, 337 (1987)].

Example 2: Further Screening of Liquid Concentrate Components

Greater glass adhesion on vertical surfaces, and decreased settling ofconcentrate components, was considered desirable. Without wishing to bebound by theory, it was postulated that natural surfactants, such as,but not limited to, lecithin would slow settlement within the liquidconcentrates, and increase concentrate viscosity by acting as athickening agent. Consequently, both liquid lecithin and solid lecithinwere evaluated (see Table 6).

Liquid lecithin dissolved into the liquid medium of each concentrate,and solid lecithin generated a partially dissolved suspension. Asindicated in Table 6, concentrates containing lecithin generallyexperienced less settlement than concentrates without (see Formula 9 and10). When PEG200 was used as the liquid medium in the presence oflecithin, the liquid concentrate gelled. Three concentrates (Table 6;Formula 3, 5 and 6) experienced minimal settlement while maintaininggood flow; these formulations were selected for further testing (seeTable 7).

It was observed that combining canola oil and liquid lecithin produced aliquid concentrate with good adhesion (Formula 3, Table 7), and thusthat liquid concentrate was further tested with cornstarch (see Table8); without wishing to be bound by theory, it was expected thatcornstarch would increase thickness and/or adhesion of hydrogels atelevated temperatures. Liquid concentrate Formula 1 of Table 8 indicatedthat addition of 20% cornstarch (relative to xanthan gum in liquidconcentrate Formula 3 of Table 7) caused viscosity to increase >5000 cP,and liquid concentrates Formula 4 and 5 demonstrated good adhesion.Further, effect of xanthan gum particle size on concentrate viscositywas also investigated (see Table 9).

Example 3: Increasing Solids Content of Liquid Concentrates

General formulation of liquid concentrate Formula 4 of Table 8 (XanthanGum:Guar Gum:Corn Starch:Liquid Soy Lecithin:Liquid Base=1 g:0.6 g:0.6g:0.1 g:2.5 mL Canola Oil) was selected for further study to determinewhat effect increasing materials content would have on a concentrate'sviscosity (see Table 10). Liquid concentrate Formula 3 of Table 10 wasthen selected for field-testing in a fire-fighting backpack and a firetruck. In order to properly test the liquid concentrate's efficacy inproducing hydrogels with a fire truck, a larger scale concentrate wasrequired.

Example 4: Scaling Up Liquid Concentrates for Fire Truck Testing

Canola-Based Concentrate

A 60 L batch of liquid concentrate Formula 3 of Table 10 was requiredfor fire-truck testing. Preparation of this 60 L concentrate batch wascarried out in in 10 L batches, with every two batches being combinedand stored in 20 L HDPE plastic pails.

To prepare 10 L of the liquid concentrate, xanthan gum, guar gum andcornstarch were added to a clean 20 L pail and pre-mixed. In a 10 Lcontainer, canola oil and liquid lecithin were mixed together with asmall paint mixer. The small paint mixer was controlled by an overheadstirrer, of which the stirring speed was varied to achieve the bestmixing efficacy. The mixing process continued until all of the liquidlecithin dissolved in the canola oil. The liquid mixture was then addedto the dry mixture, and a large paint mixer was used to disperse all dryingredients evenly throughout the oil medium. The mixer was attached toa hand drill, and the speed was varied to achieve the best mixingefficacy: first a slow speed was used to mix the dry powders with theliquid without generating any “fly-powder”, followed by a higher speedto break up and/or disperse the dry ingredients in the liquid; in someinstances, it was required to use a combination of slower and higherspeeds to break up persisting solid chunks. It took approximately 15minutes to thoroughly mix all of the dry ingredients with the liquidingredients to produce a homogeneous liquid concentrate. When two 10 Lbatches were combined to form a 20 L batch, the large paint mixer wasagain used to mix the two batches together in each 20 L pail. Theresulting 20 L liquid concentrate was given two hours to stabilize fromshear thinning before viscosity was tested to ensure consistency (seeTable 11). This procedure was repeated three times to acquire the 60 Lbatch of liquid concentrate required for fire-truck testing. Viscositiesmeasured for each 20 L batch were higher than those observed for smallersamples (e.g. Formula 3, Table 10). Without wishing to be bound bytheory, it was postulated that the viscosity difference may be caused bydifferent shear rates involved in mixing liquid concentrates on a 200 gscale versus a 10 L scale. The 20 L batch liquid concentrate was usedwithout any modification.

PEG300-Based Concentrate

A 10 L batch of PEG300-based liquid concentrate was also prepared,following the same procedure outlined above for the 60 L batch ofcanola-based concentrate. The PEG-based concentrate's final formulationand viscosity is outlined in Table 12.

Example 5: Fire Truck Testing of Large Scale Liquid Concentrates

Canola-Based Concentrate

In-field fire truck testing was completed using an 86 Hahn pumper truck,with a 1500 gallons per min (1500 gal water per min) Hale pump, on open,grass-covered ground. The liquid concentrate was pumped and mixedin-line with water within the fire truck system. After in-line mixing,the resultant hydrogel was sprayed from a fire truck hose onto avertical glass surface for adhesion testing. Samples were also collecteddirectly from the hose in 4 L beakers for on-site viscosity testing.

Initial fire truck testing involved spraying the resultant hydrogel from100′ hoses, though larger hoses, such as 200′ hoses, could have beenused. Viscosity was tested using a Viscolite 700 viscometer every minutefor 10 minutes as the hydrogel was sprayed from the hose (see FIG. 1 ).Liquid concentrate content was increased from 1 wt % to 3 wt %, and acorresponding increase in hydrogel viscosity was observed. The hydrogelsadhered to a glass test surface and formed semi-transparent films withstreaks (see FIG. 2 ). When liquid concentrate content was increased to4 wt %, viscosity decreased; however, during the glass adhesion test,the resultant hydrogel formed a uniform film that contained no visiblestreaks.

Following the initial testing, a 200′ Hose was used to observe theeffect of longer in-line mixing times. The liquid concentrate was testedat 3 wt %, 4 wt % and 5 wt % (see FIG. 3 ). Viscosity of the formedhydrogels varied in the first 5 minutes, and then tended towards asimilar viscosity. During the glass adhesion test, each hydrogel filmformed was uniform and thick.

PEG300-Based Concentrate

Fire trucking testing of the PEG300-based liquid concentrate was carriedout at 3 wt % with a 200 ft hose. During the glass adhesion test, theresultant hydrogel formed films that were uniform, but thinner thanthose observed for the canola-based hydrogels. Further, the PEG300-basedhydrogel viscosity was found to be lower, as compared to thecanola-based hydrogels (see FIG. 4 ).

Example 6: Initial Flame Tests of Initial Liquid Concentrate Hydrogels

For each flame test, a wooden paint stir stick was used in conjunctionwith a test hydrogel. An end of the wooden stir stick was coated in ahydrogel, and that coated end was then exposed to a flame from a propanetorch. How long it took for the stir stick to char and/or catch on firewas recorded (see Table 13).

Example 7: Comparison of Liquid Concentrate/Hydrogel with CurrentCommercial Products

Qualitative tests were performed to compare the herein described liquidconcentrates and their resultant hydrogels with two commerciallyavailable hydrogels (CAH), which are not composed of 100%naturally-sourced, and/or biodegradable materials: CAH1 (Barricade™) andCAH2 (TetraOK™). These comparative tests were carried out withfirefighting backpacks with 10-15 L reservoirs, equipped withhand-pumped spray-nozzles; and, an 86 Hahn pumper truck, with a 1500gallons per min (1500 gal water per min) hail pump.

With respect to forming a hydrogel from a concentrate, the hereindescribed liquid concentrates were observed to form hydrogels quicklyand readily: once the concentrate(s) was added to water, a hydrogelwould form/set within seconds, typically 10-15 s. When the concentratewas added to a firefighting backpack's water-filled reservoir, manuallyshaking the backpack several times (e.g. approximately 3-4 times) wasenough to form a hydrogel within the reservoir, and for it to be readyto use as a firefighting agent. When the concentrate was added to a firetruck's external, or on-board tank, it was observed that one personcould produce a firefighting hydrogel within minutes, typically <5 min,wherein that time included adding and mixing the liquid concentrate withwater or aqueous solution, and allowing time for the hydrogel to set.

In contrast, CAH1 generally took 15-30 min to form a hydrogel from itsliquid concentrate; and, once formed, the hydrogel typically exhibitedlow viscosity, even at a loading of 5 wt % concentrate to water. CAH2generally required extensive mixing over 8 to 10 min with multiplepeople's effort (approximately 4 people) to form a hydrogel from itssolid, powdered concentrate; often this resulted in ‘fly powder’, a finedust that coated surfaces in all directions from point of mixing. It ispossible that this fly powder can pose a health hazard to those in thevicinity. Said concentrate-coated surfaces would often convert tohydrogel-coated surfaces due to absorption of moisture from theatmosphere. Further, it was observed that the extensive mixing oftenfailed to produce a homogeneous hydrogel free of un-dissolved clumps ofpowdered concentrate, even when it was expelled from a fire hose at apressure of approximately 110 psi and having a length of 200 ft or more,and that the non-homogenous nature of the CAH2 hydrogel often causedblockages in firefighting equipment, such as spray-nozzled backpacks.

It was further observed that the herein described hydrogels offered animproved firefighting/fire-preventing performance, as compared to CAHs 1and 2, when applied to burning test edifices. For example, it was foundthat CAH1 had a very low viscosity (i.e., was runny), and did not remainon surfaces for a long enough period of time to be considered anadequate fire-prevention treatment.

In contrast, once applied to a surface, the herein described hydrogelsremained on the surfaces to which they were applied, and did not burnaway, or drip off a surface as quickly as was observed for CAH1 and/orCAH2. Further, it was observed that the herein described hydrogels had atendency to ‘creep’ or ‘ooze’ into cracks, fissures, holes in an edificeas it was applied, and then stay there: it would remain less viscous forseveral seconds (approximately 12 s), allowing it to enter any cracks orbreaks in an edifice, before its viscosity increased again due to a lackof shear forces. Such behaviour could allow the herein describedhydrogels to be used for penetrative firefighting, fire-containment,and/or fire-prevention; this behaviour, for example, could aid inextinguishing burning hay-filled barns, where having a fire-fightingagent that could penetrate into, and coat, a large smoldering hay pilewould likely be beneficial.

It was found that, in applying these hydrogels to surfaces, they couldbe applied via a straight steam, as is typically employed infire-fighting with water, or with a slight fog (percent deviation fromthe straight stream of water); a 30-40 degree fog pattern was found toprovide a uniform application of hydrogel onto most surfaces, andpenetrative fire-fighting was often well achieved with a straightstream. Further, it was observed that a ‘coat and approach’ technique tofire-fighting, suppression, and prevention with the hydrogels describedherein was often successful: coating any unburned areas with hydrogel toprevent them from catching fire, which further provided firefighterswith a safe means of egress. Coating surfaces with the hydrogels asdescribed herein was found to smother the surface, displacing oxygen afire could use to burn, and was found to cool the surface, therebypreventing the surface from becoming a potential fuel source.

TABLE 1 General formulations of select liquid concentrates LiquidConcentrate General Formulation 1 Natural Gums + Starches + VegetableOil + Surfactant 2 Natural Gums + Starches + PEG + Surfactant 3 NaturalGums + Starches + Glycerol + SurfactantI 4 Natural Gums + Starches +Vegetable Oil + PEG + Surfactant

TABLE 2 Thickening Agent Screening Results Formula Hydrogel MaterialHydrogel Set-up 1 Xanthan gum Yes 2 Guar gum Yes, but less viscous 3Xanthan gum + Guar gum (1:1) Yes 4 Carboxymethylcellulose sodium saltYes, after an hour

TABLE 3 Initial Liquid Concentrate Formulations and Test Results FormulaLiquid Concentrate wt %* Adhesion (g) 1 Xanthan Gum:Corn Starch:CanolaOil = 1 g:1 g:2.5 mL 4 0.45 2 Xanthan Gum:Guar Gum:Canola Oil = 1 g:1g:2.5 mL 3 0.62 3 Xanthan Gum:Guar Gum:PEG200 = 1 g:1 g:2.5 mL 3 0.38 4Xanthan Gum:Guar Gum:Glycerol 1 g:1 g:2.5 mL 3 0.29 5 TetraKO ™ (liquidconcentrate) 1 0.61 6 Barricade ™ (liquid concentrate) 1 0.29 Note: *Wt% is mass of liquid concentrate applied for preparing a hydrogel

TABLE 4 PEG/Glycerol-Based Hydrogel with Salt Additive Adhesion TestFormula Liquid Concentrate Formulation Na₂SO₄ Adhesion (g) 1 XanthanGum:Guar Gum:PEG200 = 0 0.38 1 g:1 g:2.5 mL 2 Xanthan Gum:GuarGum:PEG200 = 0.1 wt % 0.39 1 g:1 g:2.5 mL 3 Xanthan Gum:GuarGum:Glycerol = 0 0.29 1 g:1 g:2.5 mL 4 Xanthan Gum:Guar Gum:Glycerol =0.1 wt % 0.33 1 g:1 g:2.5 mL Note: Salt content is 0.1 wt % of liquidconcentrate applied; ali hydrogels were prepared with 3 wt % liquidconcentrate mixing with water.

TABLE 5 Canola-Based Hydrogel with Salt Additive Adhesion Test SaltAdhesion Formula Liquid Concentrate Formulation (0.1 wt %) (g) 1 1 wt %Xanthan Gum:Corn Starch:Canola Oil = 1 g:1 g:2.5 mL 0 0.35 2 1 wt %Xanthan Gum:Corn Starch:Canola Oil = 1 g:1 g:2.5 mL Na₂SO₄ 0.37 3 1 wt %Xanthan Gum:Corn Starch:Canola Oil = 1 g:1 g:2.5 mL MgSO₄ 0.19 4 2 wt %Xanthan Gum:Corn Starch:Canola Oil = 1 g:1 g:2.5 mL Na₂SO₄ 0.55 5 2 wt %Xanthan Gum:Corn Starch:Canola Oil = 1 g:1 g:2.5 mL MgSO₄ 0.41 6 3 wt %Xanthan Gum:Corn Starch:Canola Oil = 1 g:1 g:2.5 mL 0 0.62 7 3 wt %Xanthan Gum:Corn Starch:Canola Oil = 1 g:1 g:2.5 mL Na₂SO₄ 0.64 8 3 wt %Xanthan Gum:Corn Starch:Canola Oil = 1 g:1 g:2.5 mL MgSO₄ 0.62 Note:Saltcontent is 0.1 wt% of liquid concentrate applied.

TABLE 6 Settlement and Front-Flow of Liquid Concentrates after LecithinAddition Front- Xanthan Gum Guar Gum: Settlement* flow Formula SoyLecithin:Liquid Base (%) (s) 1 1 g:1 g:0.1 g (solid):2.5 mL Canola Oil 23** 26.54 2 1 g:1 g:0.2 g (solid):2.5 mL Canola Oil 16 38.31 3 1 g:1g:0.1 g (liquid):2.5 mL Canola Oil  6 61.50 4 1 g:1 g:0.2 g (liquid):2.5mL Canola Oil  0 18.44 5 1 g:1 g:0.1 g (solid):3 mL PEG200  9 70.93 6 1g:1 g:0.2 g (solid):3 mL PEG200  1 72.82 7 1 g:1 g:0.1 g (liquid):3 mLPEG200  0 9.37 8 1 g:1 g:0.2 g (liquid):3 mL PEG200  0 0 9 1 g:1 g:0:2.5mL Canola Oil 21 n/a 10 1 g:1 g:0:3 mL PEG200 18 n/a Note: Size ofxanthan gum and guar gum is 200 mesh (74 micrometers); *The test waslasted for 5 days till settlement completion; **% settlement wasconsidered to be within experimental error of Formula 9; Volume % = (topliquid layer volume/total volume) × 100%.

TABLE 7 Viscosity and Adhesion of Select Liquid Concentrates ViscosityFormula Xanthan Gum Guar Gum:Soy Lecithin:Liquid Base (cP) Adhesion (g)3; Table 6 1 g:1 g:0.1 g (liquid):2.5 mL Canola Oil 4000 0.82 5; Table 61 g:1 g:0.1 g (solid):3 mL PEG200 7100 0.72 6; Table 6 1 g:1 g:0.2 g(solid):3 mL PEG200 9300 0.54 Commercial TetraKO ™ Liquid Concentrate8600 n/a Commercial Barricade ™ Liquid Concentrate 2900 n/a Note: Alladhesion tests were carried out using hydrogels prepared with 3 wt %liquid concentrate.

TABLE 8 Effect of Starch on Liquid Concentrate Viscosity and AdhesionXanthan Gum:Guar Gum:Com Starch:Liquid Soy Lecithin: Viscosity AdhesionFormula Liquid Base (cP) (g) 1 1 g:1 g; 0.2 g; 0.1 g; 2.5 mL Canola Oil8100 N/A 2 1 g:0.5 g:0.5 g:0.1 g:2.5 mL Canola Oil 3100 0.72 3 1 g:0 g:1g:0.1 g:2.5 mL Canola Oil 1700 0.53 4 1 g:0.6 g:0.6 g:0.1 g:2.5 mLCanola Oil 3100 0.78 5 1 g:0 g:1 g:0.08 g:2 mL Canola Oil 3400 0.83 6 1g:0.5 g:0.5 g:0.025 g:3 mL PEG300 7200 0.70 Note: Size of xanthan gum is200 mesh (74 micrometers).

TABLE 9 Effect of Xanthan Gum Particle Size on Viscosity Xantham GumViscosity Particle Size Liquid Concentrate Formulation (cP) 200 μmXanthan Gum:Guar Gum: 4000 Liquid Soy Lecithin:Canola Oil = 1 g:1 g:0.1g:2.5 mL  80 μm Xanthan Gum:Guar Gum: 3200 Liquid Soy Lecithin:CanolaOil = 1 g:1 g:0.1 g:2.5 mL

TABLE 10 Effect on Viscosity of Increasing Solids Content in LiquidConcentrates Xanthan Gum:Guar Gum:Corn Starch: Viscosity Formula LiquidLecithin:Canola Oil (cP) 1 1 g:0.7 g:0.7 g:0.1 g:2.5 mL 3400 2 1 g:0.8g:0.8 g:0.1 g:2.5 mL 6000 3 1 g:0.75 g:0.75 g:0.1 g:2.5 mL 4500 4 1 g;0.6 g:0.8 g:0.1 g:2.5 mL 4600 5 1 g:0.6 g:0.9 g:0.1 g:2.5 mL 5300

TABLE 11 Viscosities of Each 20 L Batch of Canola Oil-Based LiquidConcentrate Xanthan Gum:Guar Gum:Corn Starch: Viscosity Pail LiquidLecithin:CanolaOil (cP) 1 1 g:0.7 g:0.7 g:0.1 g:2.5 mL 7200 2 7200 36500

TABLE 12 PEG300-Based Liquid Concentrate Formulation and ViscosityFormula Xanthan Gum:Guar Gum:Corn Starch:Liquid Lecithin:PEG300Viscosity (cP) 1 1 g:0.5 g; 0.5 g:0.03 g:4 mL 3500

TABLE 13 Initial Flames Tests using Initial Hydrogel Formulations Timebefore Wood Burnt (B) or Sample Concentrate Formulation Charred (C) 1 2g Xanthan Gum:2 g Corn Starch:5 mL Canola 15 s (B) Oil:200 mL Water 2 2g Xanthan Gum:5 mL PEG200:200 mL Water 30 s (C) 3 2 g Carboxymethylcellulose sodium salt:4 mL 20 s (C) PEG200:200 mL Water 4 2 g XanthanGum:1 g Corn Starch:5 mL Canola 16 s (B) Oil:200 mL Water 5 Barricade ™Hydrogel (1 wt % of liquid cone.) 15 s (B) 6 TetraKO ™ Hydrogel (1 wt %of liquid cone.) 50 s (C) 7 TetraKO ™ Hydrogel (1 wt % of dry powder)N/A Note: N/A—Hydrogel from TetraKO dry powder was very thick; onlylittle char was observed on gel surface in testing time (over 1 minute);volume of canola oil or PEG200 was volume limit for wetting dryingredients.

All publications, patents and patent applications mentioned in thisSpecification are indicative of the level of skill of those skilled inthe art to which this invention pertains and are herein incorporated byreference to the same extent as if each individual publication, patent,or patent applications was specifically and individually indicated to beincorporated by reference.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A compositioncomprising: (a) 10-75 wt % of at least one naturally-sourced thickeningagent; (b) 15-90 wt % of at least one non-aqueous liquid medium; and (c)at least one suspending agent which is a surfactant, an emulsifier orboth, wherein the composition consists of >85%, by weight, food-gradecomponents and wherein mixture of said composition with water or anaqueous solution forms a fire-suppressing, water-enhancing hydrogel. 2.The composition of claim 1, wherein the composition comprises up to 10wt % of said at least one suspending agent.
 3. The composition of claim1, further comprising one or more additives, each of which is non-toxicand biodegradable.
 4. The composition of claim 3, wherein said one ormore additive comprises a salt, an antimicrobial agent, an antifungalagent, an antioxidant, a colorant, a clay, a dispersing agent, or acombination of any two or more thereof.
 5. The composition of claim 1,wherein each of the at least one thickening agent, suspending agent andliquid medium is non-toxic and biodegradable.
 6. The composition ofclaim 1, wherein the composition has a viscosity of >1000 cP, >2500cP, >5000 cP, or >10 000 cP, when measured using a Brookfield LVDVEviscometer with a CS-34 spindle at 6.0 rpm.
 7. The composition of claim1, wherein each of the at least one thickening agent and suspendingagent is a solid or a liquid under ambient conditions.
 8. Thecomposition of claim 1, wherein the at least one thickening agentcomprises a gum, a starch or a combination of a gum and a starch.
 9. Thecomposition of claim 8, wherein the gum is guar gum, xanthan gum, sodiumalginate, agar, locust bean gum, or a combination thereof.
 10. Thecomposition of claim 9, wherein the gum is xanthan gum, guar gum, or acombination thereof.
 11. The composition of claim 8, wherein the starchis cornstarch, potato starch, tapioca, rice starch, or a combinationthereof.
 12. The composition of claim 11, wherein the starch iscornstarch.
 13. The composition of claim 1, wherein the suspending agentis lecithin, lysolecithin, polysorbate, sodium caseinate, monoglyceride,fatty acid, fatty alcohol, glycolipid, protein, or a combinationthereof.
 14. The composition of claim 13, wherein the suspending agentis lecithin, or a combination of lecithin and a fatty alcohol.
 15. Thecomposition of claim 1, wherein the liquid medium is glycerol, lowmolecular weight polyethylene glycol (PEG), or combination thereof. 16.The composition of claim 15, wherein the PEG is PEG200-PEG400.
 17. Thecomposition of claim 15, wherein the liquid medium is glycerol.
 18. Thecomposition of claim 1, wherein the composition consistsof >90%, >95%, >98% or 100%, by weight, food-grade components.